Filters, such as those used to remove contaminants from hydraulic fluid, are frequently employed in multiple assemblies in order to reduce the size of the individual filters and yet provide the desired fluid flow capacity. In the conventional multiple filter assembly, each of the filters is connected to a cast metal head, and the heads are bolted and sealed together in order to obtain the desired parallel fluid flow through the series of filters.
The castings present porosity problems so that quality assurance against leakage normally requires an inspection on a majority of parts manufactured basis.
When the cast filter head is used on pressure side applications of a pump, the porosity can result in fluid leakage, energy consumption, and potential safety hazards. When used on suction side applications, porosity of the cast head can result in the aspiration of air or other contaminants which can be extremely damaging to the pump and will detract from the smooth operation of the system.
Because of the complex configuration of the conventional filter head, the tooling cost for the cast head is extremely high. Furthermore, the tooling cost for heads capable of being attached to multiple filters is prohibitive, so that the practice in the past has been to cast heads for a single filter and then bolt the heads together in order to obtain a multiple assembly.